Am am curious what are some of your favorite things to observe on the Moon and especially want to know what about them makes them visually interesting for you? For me, here's a list of favorites that I come back to time and again and why I like them...

Schroters Valley -- Absolutely love this one when the lighting is oblique. When the shading is right the valley looks like a square of darker lava flow with the large craters Herodotus and Aristarchus and rilles within the square. With oblique lighting and a very high contrast eyepiece like a TMB Supermono it is quite a spectacular sight of contrast shades from stark contrasts to the subtle ejecta patterns and rays in the Herodotus. http://a4.pbase.com/g6/88/715088/2/70193372.F0sK70SQ.jpg

Crater Clavius -- I like the arcing chain of craters within Clavius and how they are so nicely sized from larger to smaller. Also like how the larger crater on the rim of Clavius makes it look like a diamond ring of sorts. http://home.earthlink.net/~horizon18/images/clavius.jpg

Craters Clerke-Fabbroni Region -- Probably my favorite region as the darker lava flows in this area look to me like a ghostly shaped dwarf holding a sword (upside down in the image). Apollo 17 Taurus-Littrow site is in this region. Even when flatly illuminated it remains interesting for me with the dark lava flows having shimmering little point-of-light craters dispersed mainly around the mountains just off of Crater Ching-Te. https://upload.wikimedia.org/wikipe...-Littrow_+_Dawes_+_Vitruvius_-_LROC_-_WAC.JPG

Information herein was correlated from experience, discussions, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions/opinions. Information/opinions relayed are not intended nor implied to be a substitute for professional advice.

I think they're all my favourites as well Bill lol. However, there are some others which I try to look for when conditions allow. All images were taken from the Virtual Moon Atlas and tweaked in GIMP.

The craters Theophilus, Cyrillus and Catherina to the west of the Sea of Nectar all have very interesting features internally. These include Catherina’s ghost semi-crater, the central mountains of Cyrillus, and Theophilus’ mountains with multiple summits.

Grimaldi is quite fascinating as it is normally difficult to observe. Almost large enough to be a sea in its own right, although due to foreshortening isn’t completely visible, this has to be caught about a day before Full Moon to really see any detail. I once witnessed a bright flash of presumably transient lunar phenomena in its centre. For at least twenty minutes afterwards I found sharp focusing difficult in the area even though I could achieve a sharp focus elsewhere on the visible lunar surface.

Mons Bradley in the Montes Apennines is a favourite, especially when the light catches it well. It is named after James Bradley who succeeded Edmond Halley as Astronomer Royal. I’ve had a good 360x with a 150mm Newtonian on this whole mountain range.

When caught at just the right terminator (a couple or three days after the New or Full Moon) the rille of Petavius is quite striking.

The Mare Crisium wrinkle ridge is always good to observe. Proclus, the second brightest crater on the Moon after Aristarchus, stands out well. The whole area responds well to blue filters in my experience, particularly a Wratten #82A Light Blue.

The Pyroclastic Sulpicius Gallus area (Sea of Serenity) is rich with details, nearby is the once controversial Linne feature (near the bottom of the picture), which appeared to change appearance to some nineteenth century astronomers.

Albategnius and its internal crater Klein always remind me of an aerial shot of a ruined castle and its keep.

The Sinus Medii is on the lunar prime meridian so Earth would be at the zenith to an observer standing on it. Franz von Gruithuisen believed he could see the outline of a lunar city, he named ‘Wallwerk’ not far from the Schroter crater here. The area is best observed at Last or First Quarter.

Actually I've been thinking about the time I saw the possible TLP and I've got the original VMA image with the wrong phase.

At about 23:50 British Summer Time (5/8/17) I saw a tiny rapid flash of light near the centre of the foreshortened oval of Grimaldi. I was using a 130mm Sky-Watcher Explorer Newtonian (with a Baader helical focuser) on a Sky-Watcher EQ5 mount and a TS Optics 4mm Planetary HR eyepiece for a 225x magnification, with 15‘ 28“ TFOV, and an 0.57mm exit pupil. A TS Optics (GSO) ND96-0.6 filter was threaded into the eyepiece. The Moon was just past transit (transit at 23:47) with a 96.8% illumination, azimuth 0.5° S, altitude 18°, 400, 247 km distant (Sagittarius).

A day away from Full or New Moon are the best times to observe Grimaldi as usually it is washed out and featureless. The detail, when it can be seen, can be superb.

Information herein was correlated from experience, discussions, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions/opinions. Information/opinions relayed are not intended nor implied to be a substitute for professional advice.

This may explain the often reported TLP in the area. It's interesting to point out that at the time I hadn't realised the region was such a hotbed of transient phenomena. I distinctly remember thinking 'What have I just seen?'. In an attempt to rationalise the experience I considered possible reflections from inside the OTA or even off the mount. It's quite dark where I observe from and a bright Moon lights up the area and can cause reflections off my greenhouse windows and other things. The TS Optics Planetary HR eyepieces (probably made by Barsta) can have edge of field shadows and odd reflections at times as well. The flash was definitely on the lunar surface however and seemed to emanate from the centre of Grimaldi. The other possibility was a meteor strike but it wouldn't necessarily explain the localised blurring which lasted some fifteen to twenty minutes.

I don't think I've done enough significant observing of the Moon to know what my favorites are, but Copernicus is definitely one of my favorites. It's also one of my seeing litmus tests. The other night I had seeing so good there was zero scintillation. All of that texture on the crater floor in the image Bill linked to...
...was visible in sharp relief in my 12". Ordinarily the floor looks flat and texture-less, and I can only see the central peaks and layered crater walls. But that night the crater sprang to life with incredible detail at high power. Couldn't stop looking at it.

Ill go with the Schroters Valley too has my current favorite place on the moon. I like it at the right light angle too, to see all the various strange shades and the river like features. I didn't imagined it has lava at first but.. just a river.

It looks like some kind of complex, unnatural. The first time I saw it it I was very impress and didn't know exactly what it was, there is a special beginner link with the valley.

It's a top object but I can't say if I have a favorite one.. there are so many fabulous things on the moon.

@CrazyPandain my 12". Ordinarily the floor looks flat and texture-less, and I can only see the central peaks and layered crater walls. But that night the crater sprang to life with incredible detail at high power. Couldn't stop looking at it.

I experienced that lately, getting very high details of the floor textures and being able to see much smaller craters there that are invisible even in medium conditions.

I read somewhere that smaller apertures are sometimes better for lunar viewing as air pockets tend to naturally form around 10 - 15cm. Apertures around 100mm - 150mm or even smaller can render sharper images because of this. I don't know if it's true though.

I read somewhere that smaller apertures are sometimes better for lunar viewing as air pockets tend to naturally form around 10 - 15cm. Apertures around 100mm - 150mm or even smaller can render sharper images because of this. I don't know if it's true though.

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I've heard similar things, but the logic just doesn't track for me.

At the end of the day, something is limiting your resolution. Either it's the aperture, or the atmosphere. Maybe a smaller aperture resolves less turbulence, but it also resolves less detail on the target.

I don't see any logical way in which a smaller aperture can reveal more detail than a larger aperture (despite the appearance of a sharper image).

There's also the exit pupil to consider. Smaller aperture at higher power means smaller exit pupil, which means lower contrast. This can obscure some of the more subtle features.

At the end of the day, something is limiting your resolution. Either it's the aperture, or the atmosphere. Maybe a smaller aperture resolves less turbulence, but it also resolves less detail on the target.

I don't see any logical way in which a smaller aperture can reveal more detail than a larger aperture (despite the appearance of a sharper image).

There's also the exit pupil to consider. Smaller aperture at higher power means smaller exit pupil, which means lower contrast. This can obscure some of the more subtle features.

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The "air cell" logic doesn't track with me either, and it is absurd to assume if there were such cells, that they would stay static through the entire length of the atmosphere and also just happened to be aligned with the object you were observing.

More likely the more stability smaller scopes have is probably due to several factors:
1. Smaller scopes do not have the thermal management issues of larger ones so much less self generated thermals (this is probably the biggest reason)
2. Lesser resolution of smaller scopes means they will not be able to resolve the details beyond their reach that the seeing is destabilizing, which the larger instruments can see -- so the larger apertures see more of the instability making the view sometimes not as productive.

On the issue of perhaps seeing more details than larger scopes on the Moon, well that is entirely feasible. The Moon is much more an object of extremely high contrast and high brightness features. So not a low contrast treasure trove like Jupiter. As such, larger apertures provide much brighter views at similar magnifications, and the brightness many times will overwhelm the details that are there. So the smaller scope will catch more details in the brighter features simply because their view is dimmer and allowing the hidden features to present. Now one could pump up the magnification to reduce the brightness and see them as well, but the higher magnifications means you are fighting the seeing as well. Other alternative is to use neutral density filters. In any even, I have seen the ability for the smaller scope to tease out details withing what looks like just a broad bright feature on the Moon when I take out my smaller and larger scopes together. A lot of details on lunar features remain hidden in the overly bright sunlight hitting them. So one needs to use some "tricks" to see them, like smaller scopes, filters, higher magnifications (and sometimes extreme magnifications).

Information herein was correlated from experience, discussions, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions/opinions. Information/opinions relayed are not intended nor implied to be a substitute for professional advice.

As such, larger apertures provide much brighter views at similar magnifications

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Do they though? When you look at the moon, the surface brightness is bright enough that it should shrink your pupil to be much smaller than common exit pupils of most scopes/eyepieces.

For me, there doesn't appear to be any difference in brightness on the moon for me between a 2mm exit pupil and a 7mm exit pupil, regardless of aperture. It's likely because my pupil has been constricted to less than 2mm due the brightness of the moon. In my 12" F/5, an 11mm EP looks just as bright as my 35mm EP. Maybe brightness starts to drop a bit at 10mm, and at 9mm it's definitely dimmer.

So I guess maybe if the smaller aperture is at a magnification such that its exit pupil is a wee bit smaller than your constricted pupil, then the view will be dimmer and your eye might see a smidge more detail from not being as overwhelmed. But I feel like the range in which that happens is fairly narrow. Because while you can see more detail in the highlights, you might be losing just as much detail in the shadows / low contrast regions.

The eye has quite a remarkable dynamic range, and the moon's albedo isn't *that* bright in the grand scheme of things. Maybe a few features are as bright as snow is on Earth in sunlight (which is often beyond our dynamic range), but the majority of features I would think fall well within our eye's dynamic range.

Do they though? When you look at the moon, the surface brightness is bright enough that it should shrink your pupil to be much smaller than common exit pupils of most scopes/eyepieces.

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Just like with the Sun, many times your eye cannot adjust and you need to squint as well. Same with the Moon, expecially with my 10". But also your eye will NOT adjust to the brightest feature. It is taking some sort of average or weighting of the entire scene to decide how far to contract the Iris. As a result, many lunar features will remain overblown and too brightn hiding many more details within the brightness.

And btw, this is not something I am putting forth as a conjecture or hypothesis, I see it all the time when lunar observing with multiple scopes. So it is my experience. I'm sure it is possible for others to have differing experiences since there is lots of variation in human physiology. But for me, it is quite obvious and I leverage what I have discovered in my lunar observing so routinely know the spots where more details may be hiding on the bright features, and use the techniques already mention to bright those hidden details out. One of the key areas I most enjoy is when observing a brightly lit broad mountainside. By reducing the illumination through filtering or and increasing the magnifications extreme levels to reduce the illumination, what was previously brightly lit and looked like a smooth gently sloping or rounded mountain or hill or crater wall surface then reveals some gently rounded dips and bumps along the surface, so not smooth at all like it looked when brightly lit.

So there are layers upon layers of details to be seen on the Moon if one wants. Most time people will not go to these efforts as the Moon already has orders of magnitude more details than any other celestial object, so no wanting for details that's for sure. But I have fun tweaking a little more out here and there, so no bother for me since I enjoy it.

Information herein was correlated from experience, discussions, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions/opinions. Information/opinions relayed are not intended nor implied to be a substitute for professional advice.

At the end of the day, something is limiting your resolution. Either it's the aperture, or the atmosphere. Maybe a smaller aperture resolves less turbulence, but it also resolves less detail on the target.

I don't see any logical way in which a smaller aperture can reveal more detail than a larger aperture (despite the appearance of a sharper image).

There's also the exit pupil to consider. Smaller aperture at higher power means smaller exit pupil, which means lower contrast. This can obscure some of the more subtle features.

Click to expand...

Yeah, I didn't understand it anyway. It seems over complicated. I have come on this 'air pocket' theory in at least two books. I think it's one of those mythologies which self perpetuates.

More likely the more stability smaller scopes have is probably due to several factors:
1. Smaller scopes do not have the thermal management issues of larger ones so much less self generated thermals (this is probably the biggest reason)
2. Lesser resolution of smaller scopes means they will not be able to resolve the details beyond their reach that the seeing is destabilizing, which the larger instruments can see -- so the larger apertures see more of the instability making the view sometimes not as productive.

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This seems right to me Bill. I think you've hit the nail on the head. I often use my 102mm Mak for lunar viewing, the old joke is that's all a 4" Mak is good for anyway lol. Not only can I set it up quickly, the cool down is less than 30 mins usually. I can regularly get sharp and clear views up to 170x, often more.

1. Crater Triesnecker. Plenty of high resolution targets like the rill complex, the minor craterlettes associated with the rill complex like the ones on the southern end of the rills. The G & F craters next to Crater Triesnecker. G is a double crater. There is a smaller one in between them that is also double (rarely seen as double).

2. The crater Archimedes. It is challenging to see not only the three craterlettes on the edges of its seemingly flat floor but also the finer craters scattered across the "featureless" floor.

3. The crater Plato. How many craters can you count on its floor?

4. The Pi Keys dome pit next to the crater Kies.

5. The multitude of fine craterletts surrounding the crater Torricelli.

6. The central rille in the Alpine Valley.

7. The fine craterlettes on the flat floor of Ptolemaeus.

8. The Tear Drop (serpentine) rill next to the straight wall and the craterlettes near, and embedded in this rille.

Information herein was correlated from experience, discussions, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions/opinions. Information/opinions relayed are not intended nor implied to be a substitute for professional advice.

I probably shouldn't have used the common names used in some books for these features. This is why I had stated that the Teardrop rille's (Rima Birt) location was next to the Straight Wall (another common name) which should have made it easy to find on good lunar charts or lunar photographs. Over the years it has been called the teardrop rille by some and the serpentine rille by others in books. I guess Rupes Recta & Rima Birt are less romantic for the writers. Sorry for any misleading info I MAY have given.

Not trying to start a verbal telescope performance war but for those who are curious as to where some of the "logic" came from concerning telescope performance (big scopes versus small scopes, seeing cells, etc.). Here is chapter 18 from the military handbook MIL-HDBK-141, Military Standardization Handbook, Optical Design, 5 October 1962. The info written in this chapter is extensive and is a recommended read for all telescope users. Many of us have experienced many of the atmospheric/optical/telescope phenomenon written in this chapter.

Section 18.5 covers atmospheric seeing. Lots of telescope performance, or non-performance, information is written here. For those who want to cut to the chase, please read section 18.5.2.5

BTW, this handbook was written (our tax dollars at work) by 10 experts in the optical field. 8 of them had PhD's.

Information herein was correlated from experience, discussions, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions/opinions. Information/opinions relayed are not intended nor implied to be a substitute for professional advice.